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/*
* Copyright (c) 2015 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <math.h>
#include "vp10/encoder/palette.h"
static double calc_dist(const double *p1, const double *p2, int dim) {
double dist = 0;
int i = 0;
for (i = 0; i < dim; ++i) {
dist = dist + (p1[i] - round(p2[i])) * (p1[i] - round(p2[i]));
}
return dist;
}
void vp10_calc_indices(const double *data, const double *centroids,
uint8_t *indices, int n, int k, int dim) {
int i, j;
double min_dist, this_dist;
for (i = 0; i < n; ++i) {
min_dist = calc_dist(data + i * dim, centroids, dim);
indices[i] = 0;
for (j = 1; j < k; ++j) {
this_dist = calc_dist(data + i * dim, centroids + j * dim, dim);
if (this_dist < min_dist) {
min_dist = this_dist;
indices[i] = j;
}
}
}
}
// Generate a random number in the range [0, 32768).
static unsigned int lcg_rand16(unsigned int *state) {
*state = *state * 1103515245 + 12345;
return *state / 65536 % 32768;
}
static void calc_centroids(const double *data, double *centroids,
const uint8_t *indices, int n, int k, int dim) {
int i, j, index;
int count[PALETTE_MAX_SIZE];
unsigned int rand_state = data[0];
assert(n <= 32768);
memset(count, 0, sizeof(count[0]) * k);
memset(centroids, 0, sizeof(centroids[0]) * k * dim);
for (i = 0; i < n; ++i) {
index = indices[i];
assert(index < k);
++count[index];
for (j = 0; j < dim; ++j) {
centroids[index * dim + j] += data[i * dim + j];
}
}
for (i = 0; i < k; ++i) {
if (count[i] == 0) {
memcpy(centroids + i * dim, data + (lcg_rand16(&rand_state) % n) * dim,
sizeof(centroids[0]) * dim);
} else {
const double norm = 1.0 / count[i];
for (j = 0; j < dim; ++j)
centroids[i * dim + j] *= norm;
}
}
}
static double calc_total_dist(const double *data, const double *centroids,
const uint8_t *indices, int n, int k, int dim) {
double dist = 0;
int i;
(void) k;
for (i = 0; i < n; ++i)
dist += calc_dist(data + i * dim, centroids + indices[i] * dim, dim);
return dist;
}
int vp10_k_means(const double *data, double *centroids, uint8_t *indices,
uint8_t *pre_indices, int n, int k, int dim, int max_itr) {
int i = 0;
double pre_dist, this_dist;
double pre_centroids[PALETTE_MAX_SIZE];
vp10_calc_indices(data, centroids, indices, n, k, dim);
pre_dist = calc_total_dist(data, centroids, indices, n, k, dim);
memcpy(pre_centroids, centroids, sizeof(pre_centroids[0]) * k * dim);
memcpy(pre_indices, indices, sizeof(pre_indices[0]) * n);
while (i < max_itr) {
calc_centroids(data, centroids, indices, n, k, dim);
vp10_calc_indices(data, centroids, indices, n, k, dim);
this_dist = calc_total_dist(data, centroids, indices, n, k, dim);
if (this_dist > pre_dist) {
memcpy(centroids, pre_centroids, sizeof(pre_centroids[0]) * k * dim);
memcpy(indices, pre_indices, sizeof(pre_indices[0]) * n);
break;
}
if (!memcmp(centroids, pre_centroids, sizeof(pre_centroids[0]) * k * dim))
break;
memcpy(pre_centroids, centroids, sizeof(pre_centroids[0]) * k * dim);
memcpy(pre_indices, indices, sizeof(pre_indices[0]) * n);
pre_dist = this_dist;
++i;
}
return i;
}
void vp10_insertion_sort(double *data, int n) {
int i, j, k;
double val;
if (n <= 1)
return;
for (i = 1; i < n; ++i) {
val = data[i];
j = 0;
while (val > data[j] && j < i)
++j;
if (j == i)
continue;
for (k = i; k > j; --k)
data[k] = data[k - 1];
data[j] = val;
}
}
int vp10_count_colors(const uint8_t *src, int stride, int rows, int cols) {
int n = 0, r, c, i, val_count[256];
uint8_t val;
memset(val_count, 0, sizeof(val_count));
for (r = 0; r < rows; ++r) {
for (c = 0; c < cols; ++c) {
val = src[r * stride + c];
++val_count[val];
}
}
for (i = 0; i < 256; ++i) {
if (val_count[i]) {
++n;
}
}
return n;
}
#if CONFIG_VP9_HIGHBITDEPTH
int vp10_count_colors_highbd(const uint8_t *src8, int stride, int rows,
int cols, int bit_depth) {
int n = 0, r, c, i;
uint16_t val;
uint16_t *src = CONVERT_TO_SHORTPTR(src8);
int val_count[1 << 12];
assert(bit_depth <= 12);
memset(val_count, 0, (1 << 12) * sizeof(val_count[0]));
for (r = 0; r < rows; ++r) {
for (c = 0; c < cols; ++c) {
val = src[r * stride + c];
++val_count[val];
}
}
for (i = 0; i < (1 << bit_depth); ++i) {
if (val_count[i]) {
++n;
}
}
return n;
}
#endif // CONFIG_VP9_HIGHBITDEPTH
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